Segment-level display time as implicit feedback: a comparison to eye tracking
We examine two basic sources for implicit relevance feed- back on the segment level for search personalization: eye tracking and display time. A controlled study has been conducted where 32 participants had to view documents in front of an eye tracker, query a search engine, and give explicit relevance ratings for the results. We examined the performance of the basic implicit feedback methods with respect to improved ranking and compared their performance to a pseudo relevance feedback baseline on the segment level and the original ranking of a Web search engine. Our results show that feedback based on display time on the segment level is much coarser than feedback from eye tracking. But surprisingly, for re-ranking and query expansion it did work as well as eye-tracking-based feedback. All behavior-based methods performed significantly better than our non-behavior-based baseline and especially improved poor initial rankings of the Web search engine. The study shows that segment-level display time yields comparable results as eye-tracking-based feedback. Thus, it should be considered in future personalization systems as an inexpensive but precise method for implicit feedback.